as(1) as(1)
NAME
as - Mac OS X Mach-O GNU-based assemblers
SYNOPSIS
as [ option ... ] [ file ... ]
DESCRIPTION
The as command translates assembly code in the named files to object
code. If no files are specified, as reads from stdin. All undefined
symbols in the assembly are treated as global. The output of the
assembly is left in the file a.out by default.
The program /usr/bin/as is actually a driver that executes assemblers
for specific target architectures. If no target architecture is speci-
fied, it defaults to the architecture of the host it is running on.
OPTIONS
-o name
Name the output file name instead of a.out.
-arch arch_type
Specifies the target architecture, arch_type, of the assembler
to be executed. The target assemblers for each architecture are
in /usr/libexec/gcc/darwin/arch_type/as or
/usr/local/libexec/gcc/darwin/arch_type/as. There is only one
assembler for an architecture family. If the specified target
architecture is a machine-specific implementation, the assembler
for that architecture family is executed (e.g.,
/usr/libexec/gcc/darwin/ppc/as for -arch ppc604e). See arch(3)
for the currently known arch_types.
-arch_multiple
Precede any displayed messages with a line stating the program
name (as) and the architecture (from the -arch arch_type flag),
to distinguish which architecture the error messages refer to.
When the cc(1) driver program is run with multiple -arch flags,
it invokes as with the -arch_multiple option.
-force_cpusubtype_ALL
By default, the assembler will produce the CPU subtype ALL for
the object file it is assembling if it finds no implementation-
specific instructions. Also by default, the assembler will
allow implementation-specific instructions and will combine the
CPU subtype for those specific implementations. The combining
of specific implementations is architecture-dependent; if some
combination of instructions is not allowed, an error is gener-
ated. With the optional -force_cpusubtype_ALL flag, all
instructions are allowed and the object file's CPU subtype will
be the ALL subtype. If the target architecture specified is a
machine-specific implementation (e.g., -arch ppc603, -arch
i486), the assembler will flag as errors instructions that are
not supported on that architecture, and it will produce an
object file with the CPU subtype for that specific implementa-
tion (even if no implementation-specific instructions are used).
The -force_cpusubtype_ALL flag is the default for all x86 and
x86_64 architectures.
-dynamic
Enables dynamic linking features. This is the default.
-static
Causes the assembler to treat as an error any features for
dynamic linking. Also causes the .text directive to not include
the pure_instructions section attribute.
-- Use stdin for the assembly source input.
-n Instructs the assembler not to assume that the assembly file
starts with a .text directive. Use this option when an output
file is not to contain a (__TEXT,__text) section or this section
is not to be first one in the output file.
-f Fast; no need for the assembler preprocessor (``app''). The
assembler preprocessor can also be turned off by starting the
assembly file with "#NO_APP\n". This is intended for use by
compilers which produce assembly code in a strict "clean" format
that specifies exactly where whitespace can go. The assembler
preprocessor needs to be run on hand-written assembly files
and/or files that have been preprocessed by the C preprocessor
cpp. This is typically needed when assembler files are assem-
bled through the use of the cc(1) command, which automatically
runs the C preprocessor on assembly source files. The assembler
preprocessor strips out excess spaces, turns single-quoted char-
acters into a decimal constants, and turns # <number> <filename>
<level> into .line <number>;.file <filename> pairs. When the
assembler preprocessor has been turned off by a "#NO_APP\n" at
the start of a file, it can be turned back on and off again with
pairs of "#APP\n" and "#NO_APP\n" at the beginnings of lines.
This is used by the compiler to wrap assembly statements pro-
duced from asm() statements.
-g Produce debugging information for the symbolic debugger gdb(1)
so that the assembly source can be debugged symbolically. The
debugger depends on correct use of the C preprocessor's #include
directive or the assembler's .include directive: Any include
file that produces instructions in the (__TEXT,__text) section
must be included while a .text directive is in effect. In other
words, there must be a .text directive before the include, and
the .text directive must still be in effect at the end of the
include file. Otherwise, the debugger will get confused when in
that assembly file.
-v Display the version of the assembler (both the Mac OS X version
and the GNU version it is based on).
-V Print the path and the command line of the assembler the assem-
bler driver is using.
-Idir Add the directory dir to the list of directories to search for
files included with the .include directive. The default place
to search is the current directory.
-W Suppress warnings.
-L Save non-global defined labels beginning with an 'L'; these
labels are normally discarded to save space in the resultant
symbol table. The compiler generates such temporary labels.
-q Use the clang(1) intergrated assembler instead of the GNU based
system assembler. This is available for the x86 and arm archi-
tectures. -Q Used the GNU based system assembler.
Assembler options for the PowerPC processors
-static_branch_prediction_Y_bit
Treat a single trailing '+' or '-' after a conditional PowerPC
branch instruction as a static branch prediction that sets the
Y-bit in the opcode. Pairs of trailing "++" or "--" always set
the AT-bits. This is the default for Mac OS X.
-static_branch_prediction_AT_bits
Treat a single trailing '+' or '-' after a conditional PowerPC
branch instruction as a static branch prediction that sets the
AT-bits in the opcode. Pairs of trailing "++" or "--" always set
the AT-bits but with this option a warning is issued if this
syntax is used. With this flag the assembler behaves like the
IBM tools.
-no_ppc601
Treat any PowerPC 601 instructions as an error.
FILES
a.out output file
SEE ALSO
The Mac OS X Assembler Reference in the Xcode documentation viewer:
Perform a title search for "assembler" in Apple > Developer Tools Ref-
erence Library.
The assembler source in the cctools module of the Darwin sources.
cc(1), ld(1), nm(1), otool(1), arch(3), Mach-O(5)
Apple, Inc. March 30, 2012 as(1)
Mac OS X 10.8 - Generated Sun Aug 19 15:41:27 CDT 2012